Intro to immunology Flashcards
What does the immune system need to do?
- detect threat
- respond agains threat
- minimise collateral damage
- remember the threat to respond more effectively if met next time
Do not think of the immune system as a separate entity- it is fully integrated into the body’s systems
What is the immune system?
Complex cellular and protein network that has evolved to protect the host from pathogenic microbes
Is the immune system involved in homeostasis?
YES- tissue repair
What happens if the immune system fails?
This is known as immunodeficiency disease ( immunodeficiency- SCID (severe combined immunodeficiency)) - leads to increased susceptibility to infection and sometimes cancer.
What can be the cause of autoimmune conditions?
Abnormal function or regulation of the immune system may lead to disease, e.g. autoimmune diseases, allergy
What is the normal function of the immune system?
To identify and eliminate harmful microorganisms and harmful substances such as toxins. It does this by:
- distinguishing between self and non-self ( abnormal self in the case of cancer)
- Identifying danger signals, including tissue damage (there must be some secondary danger of inflammatory signal)
The immune system must have a balance between clearing the pathogen and causing collateral damage to the host.
True/ false- bacteria reproduce faster than viruses?
true
Examples of vaccinations that have had impact on human health
Diptheria, small pox and Polio incidence has dropped considerably since the release of vaccines.
Evolution race between pathogen and host- what is this?
Pathogen and hotst exert selection pressure on each other.
The pathogen reproduces much faster than the host and can EVOLVE faster.
This is why the host has to rely on an immune system which is rapid and adaptive. Our most polymorphic genes (HLA and KIR) are involved in the immune system- this selection is due to exposure of infectious disease.
There are two strategies that the immune cells used to recognise danger (via receptors)- describe them.
- Recognise molecular patterns. There hundreds of these types of receptors (small in comparison to the second type) and they are germ line encoded.
- Recognise precise structures- there are millions of these receptors and they are made by combining gene segments to generate a HUGE VARIETY of receptors (because of the different combinations)
Advantages of the 1st strategy (recognise molecular patterns)
Many cells can express the same receptor which increases the chance of it running into the foreign material very quickly- this allows for a rapid and effective response.
Disadvantages of the 1st strategy (recognise molecular patterns)
Limited receptor diversity so there is a chance that the receptor is not complimentary to the foreign material. This means that some pathogens will not be recognised
Advantages of the 2nd strategy (recognise surface structures)
There is a mass diversity with this method- all structures have the potential to be recognised because of the random nature of the generation of receptors.
Disadvantages of the 2nd strategy (recognise surface structures)
There are only a few cells expressed with each receptor so they must be greatly expanded to generate an effective response- this can take time.
There is a chance for autoimmunity due to the random nature of the receptor generation.
The strategy that recognises molecular patterns has two types of triggers- what are they?
- PAMPs- pathogen associated molecular patterns
- DAMPs- damage associated molecular patterns
(N.B about DAMPs- when cells become damaged, they tend to release their contents)
Describe the specifity of the receptors
Each antigen receptor binds to a particular site- an epitope- a different antigen.
Each clone of B cells or T cells has a unique receptor- specific to one antigen- each cell carries many copies of this receptor on the cell surface
Describe the stages of this graph
- initially innate immunity is triggered- there is a rise in type 1 interferon levels which interferes with virus replication
- Then natural killer cells are stimulated- they recognise infected cells and lyse them- these responses help to flatten out virus replication (which is why virus conc is decreasing)
- The adaptive immune response is now needed to get rid of the virus- this will take a little bit more time
- There is now a rise in cytotoxic T lymphocytes (CTLs)- recognise and lyse infected cells.
- CTLs start to produce antibodies against the virus
How does the primary response differ from the secondary response?
The lag phase is when you don’t have a response to antigen yet. If a new antigen, will have to go through primary response.
